Die & Mould Making - CNC - Computer Numerical Control

Material properties especially influencing
machinability are:
• Surface hardness - to resist abrasive and
adhesive wear
• High content of carbides - to resist
abrasive wear
• Toughness/ductility - to resist chipping
and breakage
Dies and moulds for hot work such as die
casting and forging are used for manufacturing
of for instance engine blocks. These
dies and moulds are exposed to a number
of demanding conditions of which the
following are particularly critical for the
machinability of the tool material.
• Hot hardness - to resist plastic deformation
and erosion
• Temperature resistance - to resist
softening at high temperature
• Ductility/toughness - to resist fatigue
cracking
• Hot yield strength - to resist heat checking
Moulds for plastic materials include injection,
compression, blow and extrusion
moulds. Factors that influnence the machinability
in a plastic mould steel are:
• Hardness
• Toughness/ductility
• Homogenity of microstructure
and hardness
Die and mould material
The materials described and used as reference-material
in this guide are mainly
from the steel manufacturer Uddeholm,
with a cross reference list at the end of
the chapter.
A substantial proportion of production
costs in the die and mould industry is
involved in machining, as large volumes of
metal are generally removed. The finished
die/mould is also subjected to strict geometrical-
and surface tolerances.
Many different tool steels are used to produce
dies and moulds. In forging and die
casting the choice is generally hot-work
tool steels that can withstand the relatively
high working temperatures involved.
Plastic moulds for thermoplastics and
thermosets are sometimes made from coldwork
tool steel. In addition, some stainless
steels and grey cast iron are used for dies
and moulds. Typical in-service hardness is
in the range of 32 - 58 HRC for die and
mould material.
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